The antitumor compound howiinol A has been isolated and characterized for the first timefrom the root and stem bark of Goniothalamus howii Merr. (Annonaceae). This compound blocked the cell cycle transition from G 1 phase to S phase and inhibited the activity of topoisomerase II both inside and out side the cells. The methode of howiinol synthesis has beenstudied by the scientists of lnstitute of Materia Medica Beijiing in 1998. Herein, we describe another methode for the synthesis of howiinol A. The structure of howiinol and intermediate products were estabilished by MS and NMR spectroscopies
